pyws_clock/pyws_clock/config.py

import argparse
import configparser

from .errors import ConfigError

# Config file section
CONFIG_SECTION = 'pyws_clock'
# Maps config key name to argparse arg name and type
CONFIG_ARGS = {
    'port': ('port', int),
    'listen': ('listen_address', str),
    'session_directory': ('session_dir', str),
    'loglevel': ('verbose', int),
    'logfile': ('logfile', str),
}

def parse_config(filename:str, args:argparse.Namespace):
    """ Updates args parsed by argparse using a configuration file
        @param filename : configuration file name
        @param args : Namespace returned by ArgumentParser.parse_args()
        @return updated Namespace
        @note args is modified by reference
    """

    config = configparser.ConfigParser()
    config.read(filename)

    if CONFIG_SECTION not in config:
        err = 'There is no section named %r in %r' % (CONFIG_SECTION, filename)
        raise ConfigError(err)

    err_key = []
    for key in config[CONFIG_SECTION]:
        if key not in CONFIG_ARGS:
            err_key.append(key)
            continue
        argname, argtype = CONFIG_ARGS[key]
        setattr(args, argname, argtype(config[CONFIG_SECTION][key]))
    if len(err_key) > 0:
        err = 'Invalid configuration key in %r : %r' % (filename,
                                                        ','.join(err_key))
        raise ConfigError(err)
    return args